Ethanol and a corresponding feed co-product may be produced from a variety of feedstocks using any conventional dry mill or wet mill fermentation process known in the art. See for example, CORN, Chemistry and Technology, Stanley A. Watson and Paul E. Ramstad, editors, Published by the American Association of Cereal Chemists, Inc., St. Paul, Minn., USA, the entire contents of which are incorporated herein by reference.
Ethanol produced from fermentation of cereal grains yields co-products that are useful as animal feeds. Some of these feed co-products are known in the art as Wet Distillers Grains (WDG), Dried Distillers Grains (DDG), Wet Distillers Grains Plus Solubles (WDGS), or Dried Distillers Grains plus Solubles (DDGS). Removal of the starch component during fermentation concentrates the original protein, mineral, vitamin, fiber, and fat content. For example, dry mill ethanol production uses the starch portion of corn kernels, which is about 70% of the kernel. The starch component is converted by enzymatic hydrolysis to sugars which are then fermented to form ethanol. The ethanol is recovered by distillation. The remaining nutrients are concentrated into wet distillers grains (WDG) or Wet Distillers Grains Plus Solubles (WDGS). The WDG or WDGS may be used directly as a feed co-product or may be dried to form dried distillers grains (DDG) or dried distillers grains plus solubles (DDGS). Drying increases shelf life and improves transportability.
These grain products, as well as condensed distillers solubles (CDS) and dried distillers solubles (DDS), have been used in dairy rations for over a century. Research conducted over the past 50 years comparing these products to other protein and energy feeds has proven their value. See Armentano 1994 & 1996; Nichols et al. 1998; Schingoethe et al., 1999; Liu et al., 2000 and Al-Suwaiegh et al., 2002. DDGS has become a common component of commercial dairy protein supplements, often comprising 25-35% of the blend (dry matter basis) depending upon the price of the other ingredients. A common comparison by dairy nutritionists is that one pound of DDGS is roughly equivalent to 0.6 pounds of shelled corn and 0.4 pounds of soybean meal.
Among the grain feed components, protein has the highest value commercially while fiber has the least value. Although the nutritional value of grain feed products may vary slightly according to its source (e.g., corn, sorghum (milo), sugar beets) and crop quality, these are essentially commodity products. Accordingly, a method for improving the quality and value (i.e., increased protein content and/or decreased fiber content) of grain feed co-products resulting from ethanol production is desirable to produce grain feed products having enhanced nutritional value as compared to the grain feed products currently available from the commodity markets.